Intercoolers for gas compressors



.4.` M Y l 'momks May 26, 1964 T. E. ADAMS INTERcooLERs FOR GAS coMPREssoRs Filed June 19, 1962 May 26, 1964 T. E. ADAMS INTERcooLERs FOR GAS coMPREssoRs Filed June 19, 1962 2, Sheets-Sheet 2 INVEN TOR THOMAS Eni/MRD ADAMS United States Patent O 3,134,536 IN'IERCOOLERS FR GAS CQMPRESSRS Thomas Edward Adams, Rugby, England, assigner to Associated Electrical Industries Limited, London, England, a British company Filed June 19, 1962, Ser. No. 203,627 Claims priority, application Great Britain Jene 27, 1961 3 Claims. (Cl. 239-130) This invention relates to coolers for cooling the gas flowing between the stages of a rotary compressor. Such coolers are usually constructed as appendages mounted exteriorly around the periphery of the compressor casing and are connected between themselves and to the casing by conduits through which the gas flows. Thus the gas is required to ow out of the main casing and is reintroduced after it has been cooled. The complex circuit, part of which is internal, required to achieve this causes a considerable pressure drop between stages. Furthermore, a considerable amount of accurate machining is involved and the assembly is complicated. In addition the weight of the casings containing the coolers is considerable.

The object of the present invention is to provide an arrangement of interstage cooling for a gas compressor which introduces only a small pressure drop, which is simpler and therefore cheaper to produce, and in which there is a saving in weight as compared with the usual prior construction.

According to this invention the intercooler between two stages of -a gas compressor consists of an annular cooling structure located within the compressor casing intermediate the impellers of each stage, the gas from one stage being guided to ow through passages in the casing from the outlet of said stage directly through or around the cooler to the input of the other stage.

In a convenient embodiment the annular cooling structure consists of two semi-circular parts disposed within the main casing of a compressor intermediate the impellers, each of these parts having means for circulating a cooling medium, for example water, therethrough. Preferably each semicircular part is composed of two quadrants each containing a number of arcuate cooling tubes assembled in a framework and connected at adjacent ends to a manifold or header. The outer ends of the tubes are enclosed by end chambers which complete closed circulation paths through the quadrant. The two quadrants are supplied from a common entry connected to the manifold or header with cooling fluid which flows through the tubes in the normal manner. A common outlet for the cooling uid is connected to the header. Conveniently this outlet comprises an annular passage formed between two concentric tubes, the inner one providing the duid entry.

A preferred embodiment of the invention will now be described referring to the accompanying drawing in which FIG. 1 is a half section through the last two stages of a rotary compressor with the intercooler in position; the arrows indicate the direction of gas ow through the impellers; FIG. 2 is an end view, partly in section, of a cooler quadrant with part of an adjacent quadrant and an interconnecting manifold or header; FIG. 3 is a modication of the header shown in FIG. 1.

Referring to FIG. l, the compressor casing is represented in general by the parts 1 in which is rotatably mounted a shaft 2 with the last two impeller stages 3, 3 between which is mounted an intercooler 4 constructed in accordance with this invention.

The intercooler assembly 4 is built up of four quadrants one of which is shown in FIG. 2 by the reference 5 as comprising arcuate side plates 6 secured (as by welding) to tube end plates 7. It will be seen in FIG. 1 that the r. ICC

side plate 6 on the up-stream (right hand) side of the cooler extends radially about halfway across the tubes, whereas on the down-stream side the plate extends for the full radial width. Cooling tubes represented bythe arcs 8 are mounted between plates 6 and emerge through plates 7. Intermediate plates 9 for strengthening the structure may be provided as necessary. For convenience only eight tubes are shown in FIG. l, but it is understood that in practice the number of tubes may be around 100. To the outer end of the quadrant 5 is secured an end cap 10 which denes a chamber into which the tubes 8 emerge, thereby providing for circulation of cooling fluid.

The inner end 7 (upper end in FIG. 2) of the quadrant is secured to one side of a manifold or header 11 which is divided internally by a partition 12 into inlet and outlet chambers 12a, 12b. An inlet pipe 13 sealed into plate 12 passes through a concentric outlet pipe 14 sealed into the outer wall of the header. The other side of the header is secured to the end of an adjacent quadrant 5', the two quadrants thus forming a substantially semi-circular cooling unit with a common inlet and outlet for the two quadrants. A similar semi-circular unit will be provided in the bottom half casing.

In use, cooling fluid is supplied through inlet pipe 13 to chamber 12a, whence it flows as indicated by the arrows 8 through the tubes of each quadrant and chambers 10 to header chamber 12b and out through pipe 14. The gas flow from impeller 3 is guided within the casing directly through the cooler 4 as shown by the arrows to the inlet eye of impeller 3. It will be seen that the gas passage between stages extends over virtually the full 360 and that it is not necessary to guide the gas into localised ducts leading to the coolers, as in previous arrangements. The pressure drop between stages is, therefore, very much lower and the gas distribution far more uniform.

FIG. 3 shows a modified construction of the header of FIG. 1 designed for a 4-pass cooler; the interior is in this case divided internally by partitions 12 into three charnbers so as to provide an intermediate chamber 12C in addition to the chambers 12a, 12b. It will be seen by the yarrows that the cooling fluid passes four times through the cooler instead of twice as in FIG. 2. In other respects the construction is the same.

The tubes 8 will generally be provided with helical tins on the outside in known manner; in some circumstances it may be preferable to use tubes of ribbon wound form.

A particular advantage of the cooling structure of this invention is that, except for the small proportion of the circumference blocked by the water headers, the cooler tubes extend over the whole of the circumference of the casing, so that every particle of gas from the outlet of the ditfusers of one stage to the inlet eye of the next stage travels over almost entirely the same distance and has a similar flow path and, therefore, meets with the same resistance. Consequently every passage or part of the diffuser sees the same outlet conditions and, therefore, behaves in a similar manner to its neighbour, with the result that the machine will have the maximum turn-down range and etlicieney. Similarly the gas will be in the same condition of pressure, temperature and direction over the whole of the annulus of the inlet eye to the impeller of the next stage, because the eye of the impeller is fed by gas which comes to it uniformly from almost the complete circumference of the annular cooler.

It will be apparent that if the coolers are merely local appendages to the main casing, the flow path of the gas to the cooler from diiferent passages or parts of the diffuser of one stage will vary considerably. Similarly the flow path from the cooler to different parts of the inlet eye of the next stage will also vary considerably, with perhaps some non-uniformdistribution of gas to the impeller eye.

It will be appreciated by those skilled in the art that various constructional modifications of the embodiment described herein may be made Without departingy from the scope of the invention deiined in the appended claims.

What l claim is: 11A rotary compressor comprising:

' t (a) an outer casing;

and in which:

(d) the annular cooling structure consists of two semicircular parts;

(e) each semi-circular part is composed of two quadrants; Y

(f) each quadrant contains a plurality of arcuate cooling tubes;

(g) in each semi-circular part, a common manifold surrounds the two adjacent ends of the two quadrants;

Y (h) the remote ends of the cooling tubes of each quadrant are connected together by end chamber means to complete a path `through that quadrant for cooling fluid; i n

(i) a transverse partition divides the manifold into inlet and outlet chambers; and

, (j) two concentric pipes are connectedrespectively to the inlet and outlet chambers, the inner ot the said concentric pipes extends through a iii-st of the two chambers'and is sealed to the transverse partition through which it is in communication with the second of the two chambers, and the outer of the said y concentric pipes issealed to the outer wall of the iirst chamber of the'manifold, through which it is in communication with the rst of the two chambers.A

2. A rotary compressor comprising:

(a) an outer casing; Y

(b) a rotor mounted within the casing and provided with'a plurality of impeller stages; and

(c) an interstage cooler for Vgas undergoing compression and comprising an annular cooling structure located within said casing and located between two successive impeller stages; Y f Y Y and in which:

(d) the annular cooling structure consists of two semi circular parts;

(e) each semi-circular part is composed of'two quadrants;

(f) each quadrant contains a plurality of arcuate cooling tubes;

(g) in each semi-circular part, a, common manifold surrounds the two adjacent ends of the two quadrants;

(h) the remote ends of the cooling tubes of each quadrant are connected together by end chamber means to complete a path'throu'gh that quadrant for cooling fluid;

(i) two spaced transverse partitions divide the manifold into a rst chamber, a second chamber and an intermediate third chamber; and Y Y (j) two concentric pipes are connected respectivelyl to the iirst and second chambers, the inner of the said concentric pipes extends through the irst Vand third chambers and is sealed to the transverse partition between the second and third chambers, ,through which partition it is' in communication with the second of the two chambers, and the outer of the said concentric pipes is sealed Vto the outer wall of the iirst chamber of the manifold, through which it is in communication with the iirst of the two chambers.

3. A compressor according to claim 2, in which the said arcuate cooling tubes in each quadrant arefarranged in four radially distinct` groups, of which a radially innermost group connects the said inlet chamber and arst part of` the said end'chamber means, a fourth radially outermost group connects a second Vpart of the said end chamber means and the said outlet chamber, and the second and third radially intermediate groups connect the intermediate chamber respectively to the iirst and to the second parts ofthe said end chambermeans.

References (liteit in the iile of this patent UNITED STATES. PATENTS i Switzerland Apr. 16, 1917 

1. A ROTARY COMPRESSOR COMPRISING: (A) AN OUTER CASING; (B) A ROTOR MOUNTED WITHIN THE CASING AND PROVIDED WITH A PLURALITY OF IMPELLER STAGES; AND (C) AN INTERSTAGE COOLER FOR GAS UNDERGOING COMPRESSION AND COMPRISING AN ANNULAR COOLING STRUCTURE LOCATED WITHIN SAID CASING AND LOCATED BETWEEN TWO SUCCESSIVE IMPELLER STAGES; AND IN WHICH: (D) THE ANNULAR COOLING STRUCTURE CONSISTS OF TWO SEMICIRCULAR PARTS; (E) EACH SEMI-CIRCULAR PART IS COMPOSED OF TWO QUADRANTS; (F) EACH QUADRANT CONTAINS A PLURALITY OF ARCUATE COOLING TUBES; (G) IN EACH SEMI-CIRCULAR PART, A COMMON MANIFOLD SURROUNDS THE TWO ADJACENT ENDS OF THE TWO QUADRANTS; (H) THE REMOTE ENDS OF THE COOLING TUBES OF EACH QUADRANT ARE CONNECTED TOGETHER BY END CHAMBER MEANS TO COMPLETE A PATH THROUGH THAT QUADRANT FOR COOLING FLUID; (I) A TRANSVERSE PARTITION DIVIDES THE MANIFOLD INTO INLET AND OUTLET CHAMBERS; AND (J) TWO CONCENTRIC PIPES ARE CONNECTED RESPECTIVELY TO THE INLET AND OUTLET CHAMBERS, THE INNER OF THE SAID CONCENTRIC PIPES EXTENDS THROUGH A FIRST OF THE TWO CHAMBERS AND IS SEALED TO THE TRANSVERSE PARTITION THROUGH WHICH IT IS IN COMMUNICATION WITH THE SECOND OF THE TWO CHAMBERS, AND THE OUTER OF THE SAID CONCENTRIC PIPES IS SEALED TO THE OUTER WALL OF THE FIRST CHAMBER OF THE MANIFOLD, THROUGH WHICH IT IS IN COMMUNICATION WITH THE FIRST OF THE TWO CHAMBERS. 